Answer
Ƙarfin 'ƙuƙwalwa' shine matsi na radial da zoben ke yi a ƙasan tsagi, yana tabbatar da cewa baya juyawa ko girgiza. Wannan shine aikin 'Diamita Kyauta' ($ D_f$) ya zama karami fiye da 'Groove Diamita' ($ D_g$). Ana ba da matsin lamba $q$ ta $q = \frac{E I (D_g - D_f)}{R^2 D_g D_f}$. Tun da $I = \ frac{b t^3}{12}$, ƙarfin mannewa yana daidai da cube na kauri $t$. Don aikace-aikacen da ke da babban jijjiga (misali, watsa mota), zobe mai kauri ko mafi girma 'ƙarƙashin girman' akan $D_f$ ana buƙatar ƙara manne. Koyaya, wannan kuma yana ƙara damuwa na shigarwa $\sigma = \frac{E t c}{2 R^2}$, inda $c$ shine fadada radial da ake buƙata. Dole ne masu ƙira su warware waɗannan ma'auni guda biyu don tabbatar da cewa zoben ya tsaya a cikin sa ba tare da ɗauka ba yayin haɗuwa.
